Apparatus for forming a foot orthotic

ABSTRACT

An apparatus for forming a foot orthotic is provided including a housing for an inflatable bladder. The bladder is inflated with a hand held compressible bulb. A heat softened orthotic blank is positioned between a patient&#39;s foot and the bladder which is inflated to conform the blank to the bottom surface of the foot. The shaped blank is allowed to cool to render it nondeformable at room temperature.

BACKGROUND OF THE INVENTION

This invention relates to a method and apparatus for making correctedcustom molds for the human feet, for which orthopedic devices ororthoses, for the foot can be fabricated. Such devices are commonlyreferred to as "foot orthotics".

The human foot is formed of a complex array of twenty-six bones. Thehuman foot performs two main functions, support and locomotion. Ideally,the foot functions as a tripod, supporting the body's weight on the heeland across the metatarsal arch. The foot is capable of a wide range ofmovement. Under stressed conditions, one of the most important of thesemovements is the side to side rotation of the foot, either to theoutside ("supination") or to the inside ("pronation"). This rotationincreases or decreases the height of the foot's arch, and if excessive,can put the foot in a weakened, unbalanced, condition. The foot is saidto be in a "neutral" position when it is neither pronated nor supinated,i.e., then the heel bone is vertical and is directly in line with thetalus bone above it. The neutral position provides good skeletal supportfor the body's weight.

It is well known that activities which involve movement of the body,including walking, running, skiing, and skating, place very largestresses on the bones and joints of the leg and the foot. These stressesare larger when the bones and joints of the foot are not in the properposition, and are maximized when the knee is additionally out of properalignment.

Improper foot structure and position have been treated in part throughcustom-molded foot orthotics which fit into the shoes and which supportthe foot, or parts of the foot, in a "corrected" position. Thiscorrective function of a foot orthotic distinguished it from amass-produced foot pad or other shoe insert designed strictly forcomfort.

Orthotics are made from a custom impression or image of the foot.Impressions are typically made by plaster casting or by a mold of lowdensity foam. Images of the feet also can be made by scanning ordigitizing the foot and capturing that data in a computer database.Impressions are usually made with the subtalar joint in the neutralposition. Depending on the process used, impressions can be taken in aweight bearing, semi-weight bearing or non-weight bearing position. Atthis point, generally through a practitioner's diagnosis, adjustmentswill be made to the impression or image to correct for biomechanicaldeficiencies. These adjustments are referred to as `postings`.

Postings can be placed into two general categories. Postings whichinvolve modifications to the foot form are generally consideredintrinsic postings as making an excavation in the foot form toaccommodate a dropped metatarsal head. The result is a positivemetatarsal lift in the orthotic molded over this form. The opposite typeof posting is referred to as extrinsic. An example of this modificationis to place a pad on the foot form directly over the dropped metatarsalhead. An orthotic molded over this form has a relief pocket under themetatarsal head.

Other modifications can be added to an orthotic. These include but arenot limited to rearfoot and forefoot wedges, heel lifts and metatarsalraise pads.

Orthotics can be fabricated either manually or by an automated process.Typically, a laboratory is used to fabricate the appliance. Most labshave cast scanning capability that work either with their own millingmachine or a downstream miller. Due to the high cost of CAD-CAM milling,labs may not be able to afford their own miller. Central or sharedfabrication facilities are common. Relay stations exist which scan andmodem data to a central fabrication facility. Quite often casts arebeing measured, interpreted and then milled in three different sites andquite possibly by three different organizations. Usually, three or fourvisits to the medical practitioner are required while the shape of thepatient's foot adjusts to the orthotic in use to progress to a finalfoot shape most comfortable to the patient.

A wide spectrum of materials are available to the practitioner tofabricate an orthotic. All orthotic materials have a certain degree offlexibility and a certain degree of rigidity. Materials as common asleather and cork can be used to fabricate orthotics. Other materialssuch as ethylene vinyl acetate (EVA), polyethylene and polypropylene areemployed. These materials can be used alone or in combination with eachother. Also important to the function of the orthotic is thickness andform.

There are several problems associated with the existing methods forfabricating foot orthotics. The single largest disadvantage is theimpression processes employed. They do little to change the positioningand/or alignment of components of the foot. The molding and scanningprocesses used simply duplicate the structure of the foot. Allmodifications are done through the evaluation of the practitioner.Education and experience aid a practitioner in making proficientadjustments. However, these adjustments are still based on judgement.

Another disadvantage to the present processes is the time delayassociated with fabricating the orthotic. Once the impression of aperson's feet have been taken, a wait of several days or even severalweeks is usually required before the orthotic is finished. When apatient has come to a practitioner with a foot problem, they usuallyrequire a remedy as soon as possible.

The break-in period associated with most presently available orthoticsis also a disadvantage. Since modifications and adjustments to theimpression are based on the inexact ability and judgement of thepractitioner, the fabricated orthotic is often too uncomfortable for aperson to wear for long periods of time when they first begin to wearit. Often, patients are told to wear the orthotics for short periods oftime every day, increasing the amount of time over a period of weeks.

It has been proposed in U.S. Pat. No. 1,044,171 to form an arch supportby utilizing a flexible bladder upon which an arch support blank rests.The bottom of the patient's foot is placed on the arch support and thearch support is heated by heating gas from a compressed gas supply whichthen is directed into the bladder. The bladder becomes inflated whilethe blank is softened by the heated gas. The softened blank then isconformed to the shape of the patient's arch by the pressurized bladder.The gas directed to the bladder is heated from a heater which heats theconduit through which gas is supplied to the bladder. After the blank isconformed to the shape of the patient's arch, the heated gas in thebladder is replaced by cool gas directed into the bladder while theheater is inactivated. The cool gas causes the shaped blank to hardeninto a permanent shape at normal room temperature.

The method and apparatus described in U.S. Pat. No. 1,044,171 hasdisadvantages which render their use undesirable. Since the apparatusrequires a source of compressed gas, the storage tank for the compressedgas must be capable of withstanding high pressure. This requirement, inturn, necessitates use of a strong and heavy material for the storagetank. Also, since the conduit between the gas supply must be heated, itmust be formed of material, most usually a metal which must conduct heatbut which is not degraded by heat. Thus, the conduit, must be formed ofa heavy material. These two requirements render the apparatusnonportable by hand. This requirement is undesirable since the apparatuscannot be delivered easily to the site of the patient.

In addition, since the gas control apparatus is positioned beneath thepatient's foot to accommodate the heater, it is inconvenient to accessthe control apparatus. In any event, the control apparatus cannot becontrolled by the patient who is best able to determine the pressure atwhich the foot is most comfortable when forming the foot orthotic.

In addition, since the patented method and apparatus require the blankto be heated while in contact with the patient's foot, portions of theblank remote from the bladder such as at the back of the heel or at thefront of the toes are difficult to heat in that longer heat times and/orhigher temperatures are required. Neither process condition iscomfortable for the patient.

Furthermore, the patented method and apparatus does not provide a recordof conditions at which an orthotic is formed. This lack of a recordhinders the medical practitioner during patient visits subsequent to thefirst visit when the orthotic is reshaped. If such a record existed, themedical practitioner would be provided with a convenient starting pointcondition to effect the orthotic reshaping.

Accordingly, it would be desirable to provide a method for forming footorthotics with an apparatus which is hand portable. In addition, itwould be desirable to provide such a method and apparatus which quicklyand accurately provides an orthotic which conforms with the entireweight supporting surface of the foot. Furthermore, it would bedesirable to provide such a method and apparatus which can be easilyadjusted to a variety of foot sizes. Also, it would be desirable toprovide such a method and apparatus which provide a record of orthoticforming conditions over a plurality of orthotic forming events.

SUMMARY OF THE INVENTION

The present invention provides a method for forming a foot orthotic witha hand portable apparatus. The apparatus comprises an inflatablebladder, means for positioning a seated patient's foot in a stationaryposition on the bladder and means for positioning a heat softenedorthotic blank between the bladder and the patient's foot. The bladderinterior is pressurized by hand held pressuring means either by thepatient or by a person assisting the patient. The hand held pressurizingmeans includes a hand-deformable resilient bulb, a one way valve, whichwhen open, provides fluid communication between the bulb interior andthe bladder through a conduit. When the bladder is to be depressurized,such as after the orthotic is removed, a valve, such as a release valvein fluid communication with the conduit is opened to effect removal ofpressurized gas from the bladder. One or two pressurizable bladders areprovided so that orthotics can be formed for the patient for one or bothfeet. In one aspect of this invention, a pressure gauge for each bladderwhich indicates the pressure at which the formed orthotic is renderednon-deformable at normal room temperature.

In the operation of the method and apparatus of this invention, anorthotic blank, heated to above its heat deformation temperature ispositioned between a bladder and a seated patient's foot. The hand heldbulb then is hand-squeezed to inflate the bladder to a pressure suchthat the blank is deformed to a form to conform to the bottom surface ofthe foot and to positively raise the bony or structural parts of thefoot, including the arch of the patient. Bladder inflation then isstopped and the formed blank is allowed to cool to a temperature belowits heat deformation temperature. The pressure at which bladderinflation is stopped is noted from the gauge which indicates the bladderpressure. The release valve then is opened to allow the pressure withinthe bladder to be reduced to substantially atmospheric pressures. Theapparatus then is in condition for a repeated operation to form a secondfoot orthotic.

Since a storage tank for pressurized gas and conduits which are capableof being heated to a temperature to soften a blank are eliminated, theapparatus of this invention can be rendered hand portable. In addition,since the conduit directing air to the bladder can be formed of anonmetallic flexible material such as rubber or a polymeric composition,the hand squeezable bulbs can be located in a comfortable position forthe user rather than being located in a remote position, such as beneaththe patient's foot. Furthermore, a record of the bladder pressure atwhich the orthotic is formed provides the user with a convenientstarting pressure for the next orthotic fitting during which thepreviously formed orthotic is further deformed to accommodate changes inthe patient's foot shape primarily due to use of the previously formedorthotic.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of the apparatus of this invention.

FIG. 2 is a cross-section view of this invention showing the connectionbetween a bladder and a hand held pressurizing bulb.

FIG. 3 is a top view of an alternative embodiment of this inventionutilizing a three way valve.

FIG. 4 is a top view of an alternative embodiment of this invention.

FIG. 5 is a top view of an orthotic blank useful with the presentinvention.

FIG. 6 is a cross sectional view of the blank of FIG. 5 taken along line6--6.

DESCRIPTION OF SPECIFIC EMBODIMENTS

The present method and apparatus of this invention effects repositioningthe metatarsal bones by working in conjunction with the foot muscles.The pressures created by the inflated bladder distribute the forces in amanner consistent with the foot's natural shape. The method andapparatus of this invention eliminates the need to manually incorporatepostings or additions and wedges. By repositioning the metatarsals, thecalcaneus returns to a normal position. In turn, this provides correctalignment of the subtalar component and therefore the entire bodyposture.

After the initial fitting, the patient typically requires two additionaladjustments. Adjustments are made by taking a new impression either fromthe previously formed orthotic or a new orthotic blank with the inflatedbladder. The typical time frame between an initial fitting andsubsequent adjustments is two to three weeks. This allows time for themuscles in the foot to work in conjunction with the orthotic to bringthe metatarsals back to a more normal position.

Referring to FIGS. 1 and 2, the apparatus of this invention 10 includesa housing 12 having a top plate 13. Top plate 13 is positioned at anangle A between about 0° and 45°, preferably between about 15° and 30°from the horizontal 15 so that a seated patient exerts little or no bodyweight, other than the weight of the foot on a bladder 18 or 20. Thisposition provides comfort for the patient and accuracy of orthotic fit.Inflatable bladders 18 and 20 are received within housing openings 14and 16. Straps 22 and buckles 24 are positioned to secure an ankle andstraps 26 and buckle 28 are positioned to secure a toe section of afoot. A heel support 30 is slideably mounted on slide bar 32. Theposition of heel support 30 is adjusted by loosening thumb screw 19 toaccommodate feet of varying sizes on bladders 18 and 20. When thedesired foot position is established, screw 19 is tightened to set theposition of heel support 30. Gauge 36 is connected to the interior ofbladder 18 through conduit 40 and indicates the pressure within bladder18, typically between 0 and about 5 psi. Gauge 34, of the same type asgauge 36, indicates the pressure within bladder 20.

Hand held compression bulb 38, made of a flexible material such asrubber, is in fluid communication with conduit 40 which, in turn is influid communication with the interior of bladder 18. Shut off valve 44is opened while one way valve 41 is closed when the pressure on bulb 38is increased to admit pressurized gas into conduit 40. When pressure onbulb 38 is decreased or eliminated, release valve 42 is closed toprevent pressurized gas from exiting bladder 18 and one way valve 41 isopen to admit gas into the compression bulb 38. After the desiredpressure in bladder 18 is attained during which time a heat-softenedorthotic blank 46 (FIG. 2) becomes hardened so that it is nondeformableat room temperature, shut off valve 44 is opened to decrease pressurewithin bladder 18 to about atmospheric pressure.

As described above with reference to bulb 38 and bladder 18, bulb 50,connected to conduit 52 is also in fluid communication with one wayvalves, and a release valve which function as described above withreference bulb 38, valves 42 and 44 and bladder 18. Gauge 34 indicatespressure within bladder 20 and is of the same type as gauge 36.

Referring to FIG. 2, the method of this invention is described. A blank46 for a foot orthotic previously heated to above its softeningtemperature is placed on bladder 18. The blank can be convenientlyheated by immersing it in hot water or the like. A patient's foot 60 ispositioned on the softened blank. The position of the heel rest 30 ismoved when adjustable thumb screw 19 is loosened and is moved on slidebar 32. The foot 60 is positioned securely by straps 26 and 22. Bulb 38then is hand squeezed to increase pressure within bladder 18 until theheated blank 46 comfortably conforms to the bottom surface of the foot60. The bladder pressure is maintained until the formed blank is cooledbelow its heat softening temperature. The formed orthotic thus conformsto the shape of the bottom of foot 60 after the impaired bony andstructural parts of the foot are raised at normal room temperature. Thestraps 22 and 26 are released to free the foot 60 and the pressure inbladder 18 is reduced by opening shut off valve 44.

Referring to FIG. 3, where the same reference numerals as used in FIG. 1refer to the same elements, an alternative embodiment of this inventionis illustrated utilizing a single hand squeezable bulb 64 for bothbladders 18 and 20. The bulb 64 is in fluid communication with conduit66, which, in turn, is in fluid communication with three way valve 68which controls fluid communication between conduit 66 and conduits 70and 72. Conduit 70 is in fluid communication with bladder 18 and conduit72 is in fluid communication with bladder 20. Shut off valve 74 is influid communication with conduit 70 and shut off valve 76 is in fluidcommunication with conduit 72. Bulb 64 and release valves 74 and 76 andbladders 18 and 20 function in the same manner as described above. Threeway valve 68 controls fluid pressure in bladder 18 and 20.

Referring to FIG. 4, an embodiment of this invention is shown which iscapable of forming one foot orthotic at a time. Numerical designationsthe same as the numeral designations of FIG. 1 refer to the sameelements. In operation, the patient's foot is placed on a heat softenedorthotic precursor (not shown) which, in turn, is positioned on bladder20. The foot is secured by straps 22 and 26 and buckles 24 and 28. Theheel rest 31 is positioned by adjustable thumb screw 51 on slide bar 32.The screw 51 is secured on slide bar 32 when the foot is in the properposition. The bulb 38 then is hand squeezed to increase pressure withinbladder 20 until the foot is desirably positioned in the orthoticprecursor. The orthotic is then allowed to cool between its heatsoftening temperature so that the orthotic has a permanent shape at roomtemperature.

Referring to FIG. 5 and 6, a blank 70 is useful with the method andapparatus of this invention is illustrated. The blank includes twoelements 71 and 73 adhered together or a single element shaped as shown.The first element 71 is shaped to the general shape of the interiorbottom surface of a shoe. It is of necessity thin, i.e., between about1/32 and about 3/32 inch thick. The first element 71 is stiffened bysecond element 73 which has a thickness between about 3/32 and about5/32 inch. The width of the second element 73 is between about 70% and100%, preferably between about 70% and about 80% of the width of thefirst element and a length between about 75% and about 85% of the lengthof the first element. The blank 70 is formed of a material having asoftening temperature between about 65° C. and about 85° C., preferablybetween about 70° C. and about 80° C. The blank is formed from a heatsoftenable polymeric composition such as polyethylene, polypropylene,ethylene vinyl acetate (EVA), polytransisoprene or the like, preferablypolytransisoprene composition such as is available from Smith & Nephew,Roylan, Inc., (of Germantown, Wis.) under the tradename San-Splint. Thediameter of the curved heel section 81 from center 80 of the firstelement is between about 1 and about 11/2 inch, preferably between about11/8 and 13/8 inch. The diameter of the curved heel section 83 of thesecond element from center 80 is between about 3/4 and about 1/4 inch,preferably between about 7/8 and 11/8 inch.

We claim:
 1. A hand portable apparatus for forming a foot orthotic for a patient in a seated position which comprises:a housing having a top surface positioned at an angle between about 0° and about 45° with reference to a horizontal surface upon which said apparatus rests, at least one inflatable bladder positioned at said top surface, means for inflating with a gas said at least one inflatable bladder with a hand held compressible bulb, having a one way valve, in fluid communication with said bladder through a hollow conduit having successively a release valve and a shut off valve to a pressure to raise bone portions of a foot of a patient to a normal position for said bone portions when said bladder is inflated in contact with a deformable blank for a foot orthotic in contact with said foot, means for seating said patient such that the seated patient exerts little or no body weight other than the weight of the foot on the bladder, and means for securing the foot of said patient in a stationary position during a time said foot is in contact with said deformable blank.
 2. The apparatus of claim 1 including two inflatable bladders, each being in fluid communication with a separate hand held compressible bulb.
 3. The apparatus of claim 1 including two inflatable bladders, each being in fluid communication with a single hand held compressible bulb.
 4. The apparatus of any one of claims 1, 2 or 3 wherein said hollow conduit is formed from a flexible composition.
 5. The apparatus of any one of claims 1, 2 or 3 including a pressure gauge which indicates pressure within said at least one inflatable bladder.
 6. The apparatus of claim 4 including a pressure gauge which indicates pressure within said at least one inflatable bladder. 